Search

Endometriosis and adenomyosis are characterized by the presence of ectopic endometrium, but are also associated with functional and structural changes in the eutopic endometrium and inner myometrium. Alterations in the inner myometrium occurring in women with endometriosis and adenomyosis may be at the root of a defective remodelling of the myometrial spiral arteries from the onset of decidualization and result in vascular resistance and increased risk of defective deep placentation. The association of major obstetrical syndromes and different types of defective remodelling of the myometrial spiral arteries has been well documented. The possibility of a link between both endometriosis and adenomyosis and some major obstetric syndromes remains controversial because of at least two factors: first, changes of the inner myometrium are frequently present in women with endometriosis but the diagnosis requires high-resolution imaging such as magnetic resonance which is not routinely performed and second, patients with endometriosis are frequently subjected to prolonged hormone suppressive therapy. Indeed, there is evidence that pre-treatment with a Gonadotropin Releasing-Hormone analogue can improve the uterine microenvironment and implantation rate following IVF in infertile patients with endometriosis., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Objectives: Placenta creta is an increasingly prevalent cause of maternal morbidity/mortality. Decidua is at least focally defective and extravillous trophoblast (EVT) may be abnormal. The study aims to compare differences in migratory trophoblast and spiral artery remodeling between areas with and without decidua at the placental implantation site., Study Design: Sixteen (12 creta, 4 non-creta) caesarean hysterectomy specimens were studied immunohistochemically. Invasive EVT and multinucleate trophoblast giant cells (MTGC) were quantified; confluent EVT (>5 opposed EVTs) and spiral artery remodeling were assessed semi-quantitatively., Results: In 6 cases, placenta creta was focal. Compared to placenta creta with local decidua, cases without local decidua had increased interstitial EVT cells (×200 field) (SEM 45.6 [4.9] vs. 80.5 [3.9], p < 0.0001), fewer multinucleate trophoblast giant cells (expressed as a percentage of total EVT) (0.8 [0.3] vs. 31.5 [2.2]% p < 0.0001) and EVT was more confluent (p < 0.0001). In contrast, placenta creta cases with local decidua had a greater degree of spiral artery remodeling (mean remodeling score 1.65 [0.07] vs. 1.13 [0.05], p < 0.0001) associated with increased intramural trophoblast (p = 0.0008). The only difference between placenta creta with local decidua and normal placentation cases was an increased number of interstitial EVT cells in creta cases (45.6 [4.9] vs. 24.8 [3.2], p = 0.04)., Conclusions: Numbers of interstitial EVT are increased in placenta creta, more so in cases without local decidua. Despite this spiral artery modeling is reduced in placenta creta cases with no decidua. The results emphasize the crucial role of decidua in control of trophoblast invasion and spiral artery remodeling., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Calreticulin is a calcium binding, endoplasmic reticulum resident protein best known for its roles in intracellular calcium homeostasis and the quality control processes of the endoplasmic reticulum. There is evidence for a range of activities for calreticulin outside the endoplasmic reticulum, including in the cytosol, on the surface of different cells types and in the extracellular matrix. Recent evidence indicates that human pregnancy is a condition of elevated circulating calreticulin. Calreticulin was increased in the plasma of women throughout pregnancy compared to the non-pregnant state. Calreticulin was also further increased during the hypertensive disorder of human pregnancy, pre-eclampsia. To clarify the roles of circulating calreticulin in pregnancy and pre-eclampsia, the aim of this study was to determine the effects of exogenous calreticulin on two cell types that are relevant to normal human pregnancy and to pre-eclampsia. Human primary myometrial microvascular endothelial cells (UtMVEC-Myo) and the human trophoblast cell line, HTR8/SVneo, were cultured with exogenous calreticulin at concentrations (2 μg/ml and 5 μg/ml) comparable to that measured in maternal blood. The higher concentration of calreticulin significantly increased the migration of the UtMVEC-Myo cells, but significantly reduced the migration of the HTR8/SVneo cells. In the presence of only FGF, FBS and antibiotics calreticulin at 5 μg/ml significantly reduced the number of UtMVEC-Myo cells during in vitro culture for 120 h. These results demonstrate that exogenous calreticulin can alter both HTR8/SVneo and UtMVEC-Myo cell functions in vitro at a (patho-) physiologically relevant concentration. Increased calreticulin may also contribute to altered functions of both cell types during pre-eclampsia., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Introduction: To evaluate whether 3D placental and myometrial power Doppler blood perfusion in the first trimester can be used to detect risk pregnancies., Methods: 3D power Doppler vascularization index (VI) and flow index (FI) of the entire placenta and the neighbouring myometrium were separately measured in the first trimester in all women with singleton pregnancies during a period of three months. In addition we measured placental volume, placental quotient, PAPP-A, as well as uterine artery at 12 and 22 weeks (mean PI and mean notch) and compared those data with the pregnancy outcome., Results: Data from 383 women could be evaluated. 10 developed pre-eclampsia (PE). Both flow and vascularization were markedly lower in the placentas compared to the adjoining decidua and myometria. There was some correlation between placental vascularization Index (PVI) as well as deciduo-myometrial vascularization index (MVI) and placental volume, PAPP-A and number of pregnancies and a marked correlation between PVI and especially MVI to mean notch at 12 weeks and 22 weeks (PVI: -0.215, -0.274 MVI: -0.316,-0.322). PVI and MVI were significantly reduced in women with pregnancy problems and showed the greatest reduction in PE-pregnancies (p: 0.0018, 0.0004). Of all measured parameters MVI showed the best sensitivity for the detection of PE., Conclusion: The correlation between PVI and MVI in the first trimester and mean notch in the second shows that they provide valuable information at as early as 12 weeks which normally so far is only available at 22 weeks by uterine artery Doppler flow. As MVI measures the percentage of vessels in the deciduo-myometrial area it could also provide information on trophoblast invasion. This hypothesis is supported in particular by a marked decrease of the MVI in pregnancy problems especially in PE-pregnancies., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Agonist-induced tone oscillations (rhythmic contractions and relaxations) occur in vascular beds to allow acute regulation of volume flow and thus the delivery of oxygen and nutrients to the tissue. Mechanisms responsible for the control of human placental vasomotor tone and blood flow are poorly characterized. This study aimed to characterise thromboxane-induced tone oscillations in human placental and myometrial arteries. Chorionic plate and myometrial arteries obtained from biopsies at term were mounted for isometric tension measurement. Tone oscillations were observed in chorionic arteries only when exposed to sub-maximal (<1 microM) concentrations of U46619. Slow (mean+/-SEM) frequency (2.6+/-0.5 per hour), large amplitude (39+/-7% of peak contraction) tone oscillations were elicited by 0.03 microM U46619 (n=18). In the presence of the nitric oxide synthase (NOS) inhibitor l-NNA (100 microM) the amplitude was significantly reduced (40+/-13% to 18+/-8%, P<0.05, n=6), frequency was unaltered and the bradykinin-dependent vasodilator response was reduced (68+/-13% to 40+/-19%, P<0.05, n=6). Myometrial arteries exposed to 1 microM U46619 developed tone oscillations within 10 min, which increased in amplitude over 30min occurring at relatively constant frequency. The mean amplitude of oscillations at 30 min (31+/-7%, n=16) was similar to that in chorionic arteries but the occurrence more frequent (42.8+/-9.7 per hour, P<0.001). Inhibition of NOS did not alter tone oscillations in myometrial arteries. Tone oscillations in chorionic arteries from pre-eclamptic and growth restricted (FGR) pregnancies were reduced in amplitude whereas those in myometrial arteries had increased frequency. Inhibition of NOS further reduced oscillation amplitude in chorionic arteries from FGR pregnancies. The alterations may contribute to the vasculopathology of these conditions, or, may represent compensatory mechanisms to maintain a matching of materno-placental blood flow.

The ability of a blood vessel to develop tone is dependent upon morphological parameters of the smooth muscle cells (SMC), including density, relationship with the endothelium and subcellular distribution of myofilaments and intracellular organelles. Consequently, wall ultrastructure of isolated human placental chorionic plate arteries (n=12), fixed when pressurised to mimic their in vivo geometry, was examined qualitatively using electron microscopy, and compared with maternal arteries (omental, n=10, myometrial, n=6). Arteries from women with uncomplicated pregnancy were tested for contractile viability before fixing, with some vessels post-fixed in osmium-ferricyanide for sarcoplasmic reticulum (SR) identification. In contrast to maternal arteries, placental arteries had no internal elastic lamina but exhibited considerable extracellular matrix separating circularly orientated SMC. Human SMC contained tightly packed arrays of myofilaments running parallel to the plasma membrane, enveloping cellular organelles. Synthetic SMC, with few myofilaments and much rough SR, were observed in placental arteries only. SR in SMC from maternal arteries was located centrally, often encircling mitochondria, and also near the plasma membrane associated with caveolae. Positive SR staining was rarely observed in SMC of placental arteries. This study highlights ultrastructural differences between placental and maternal arteries that may underlie specialised mechanisms of regulating vascular tone in the placenta.

The involvement of endovascular trophoblast in fibrinoid deposition, replacement of the endothelium and vascular smooth muscle breakdown is studied in spiral arteries of the mesometrial triangle from day 15 to day 21 of rat pregnancy, by examining arterial cross sections after staining for cytokeratin, PAS, CD31 and alpha-actin. From day 15 to day 18 of pregnancy, fibrinoid deposition underneath the endovascular trophoblast increases gradually, whereas the amount of endovascular trophoblast in invaded arteries remains constant. CD31 staining is significantly reduced in sub-ET (= underlying the endovascular trophoblast) as compared to extra-ET (= outside the endovascular trophoblast) and no-ET (= non-invaded arterial sections) at each time-point of pregnancy examined (P < 0.005 and P < 0.0005 at each day of pregnancy), whereas alpha-actin staining is reduced both in sub-ET and in extra-ET as compared to no-ET. During pregnancy, CD31 staining in sub-ET initially declines, but increases significantly on day 21 (P < 0.001 versus d20) suggesting re-endothelialization of the vascular wall. In conclusion, changes in spiral arteries of pregnant rats reveal striking similarities with physiological changes seen in human pregnancy, thus emphasizing the usefulness of this species as an experimental model for studying normal and complicated pregnancies in humans.

Pregnancy-induced structural changes in spiral arteries seem to be a prerequisite for successful fetal outcome in humans. It is unknown whether these changes also occur in other preplacental vessels (radial and arcuate arteries) in normal pregnancies. Since the radial and arcuate arteries need to dilate in order to accommodate the increase in placental blood flow during pregnancy, it is expected that they are also invaded by trophoblast and respond with structural changes. The objective of the present study was to evaluate the extent of trophoblast invasion in the guinea-pig preplacental vasculature and its effect on the vascular structure of mesometrial, myometrial and arcade arteries. Under general anaesthesia the vascular system of non- (n = 4), mid- (n = 4) and late- (n = 8) pregnant guinea-pigs was fixed by immersion or perfusion. Cross-sections of immersion-fixed mesometrial and arcade arteries were stained with toluidine blue. Cross-sections of perfusion-fixed mesometrial, myometrial and arcade arteries were stained with haematoxylin-eosin, Elastica van Gieson staining and antibodies against alpha-smooth-muscle-actin (ASMA), cytokeratin and factor VIII, to detect vascular smooth muscle, trophoblastic, and endothelial cells, respectively. In addition, the external and internal vascular circumference of sections from perfusion-fixed tissue was determined. All cross-sections were evaluated by light microscopy. In the course of pregnancy, progressive endothelial swelling, disappearance of the elastic lamina interna and disarrangement of the tunica media were observed in the myometrial and throughout the mesometrial arteries up to the junction with the arcade arteries. These changes coincided the migration of keratin-positive staining giant cells. It is concluded that in normal guinea-pig pregnancy, structural changes occur in the entire mesometrial artery and at least a part of the myometrial artery, although such changes were not seen in the arcade artery.

The process of placentation in the macaque has been extensively studied and found to resemble closely that observed in the human. In this model, histopathologically, intervillous flow is anticipated from week 3 post-conception. We set out to document the nature and onset of intervillous flow in the macaque in vivo using colour Doppler imaging (CDI), colour Doppler energy (CDE) and pulsed-wave Doppler (PWD). Pregnant females were assessed between 15-50 days gestation (term = 165 days) with an Acuson 128/XP10 high-resolution ultrasound scanner, using a 7-MHz linear array probe. The placenta, subjacent decidua and myometrium were assessed using CDI and CDE. Specific regions of flow were interrogated using PWD; the resulting flow velocity waveforms were stored and quantified using conventional Doppler indices. B-mode sonography was able to demonstrate the well-defined placental-decidual interface observed in this species; CDI and CDE clearly visualized the uteroplacental vasculature. Spiral arteries were followed to their point of discharge into the intervillous space, and PWD at these sites obtained a characteristic flow velocity waveform. The indices obtained confirmed a flow of low resistance and pulsatility throughout the gestation studied. Flow within the intervillous space was noted from day 20 of gestation.

The effects of pregnancy and placental localization on vascular responses to endogenous vasoconstrictor agents were studied in intramyometrial arteries dissected from myometrial biopsies. The tissues were taken from the lower uterine segment in patients subjected to hysterectomy (n = 8), and in pregnant patients undergoing caesarean section without (n = 8) and with low anterior placental insertion/placenta previa (n = 8). Isometric tension was recorded in vascular ring preparations mounted in organ baths and the contractile effects of angiotensin II, noradrenaline, vasopressin and the TxA2-mimic U46619 were studied. No differences in contractile responses between vessels from the three patient groups were found. When comparing vessels from all the pregnant patients with those from non-pregnant patients, vasopressin showed lower Emax values in preparations from the pregnant women, but otherwise no differences were found. The pD2 values (= -log EC50) ranked the agonists vasopressin greater than U46619 greater than or equal to angiotensin II greater than or equal to noradrenaline (U46619 greater than noradrenaline), while no major differences emerged for the Emax values. The results do not provide evidence that pregnancy and placental localization produce major changes in intramyometrial vascular responses to endogenous vasoconstrictor agents of suggested importance for regulation of human maternal placental resistance.

Morphometric and statistical techniques were used to assess the relation of myometrial interstitial trophoblast to the uteroplacental vasculature in 27 intact hysterectomy specimens ranging from 8 to 18 weeks' gestation. It was found that the volume density of cytotrophoblast in the myometrium and in particular the proximity of such trophoblast to the placental bed spiral arteries correlated significantly with morphological alterations in these vessels. The changes included swelling of endothelium, hypertrophy of individual medial smooth muscle cells, and oedema and disruption of the architecture of the vessel wall as a time-related continuum. Some of the changes, such as swollen endothelium and basophilia of medial smooth muscle cells were noted also in spiral arteries in the non-placental bed endometrium but to a considerably less extent than in the placental bed. Intimal vacuolation was common to placental bed and non-placental bed arteries, increased with gestational age and can be considered as a non-specific feature. The migration of endovascular trophoblast into the myometrial spiral arteries in the second trimester occurred only when these arteries had been considerably altered in their morphology. These findings indicate that migratory interstitial cytotrophoblast probably has a role to play in the preparation of the myometrial segments of the uteroplacental arteries for the second wave of endovascular trophoblast migration that occurs in the second trimester of human pregnancy.

The Xe-133 clearance method, chosen by several groups for indirect placental blood flow (PBF) determination, is evaluated using a placenta-fetus compartment model first introduced by Moll (1973). The placenta is modelled as a strong concurrent, counter-current or cross-current exchange system. The fetal circulatory system is simplified by dividing it into two major branches: the umbilical circulation and the fetal tissue or systemic circulation. Following an arbitrary labelling of maternal arterial blood, Xe-133 concentrations in myometrium, placenta and fetus are derived from the model and are used to calculate placental clearance rates. The dependence of clearance rates on maternal and fetal PBF, on the distribution of fetal cardiac output, and on the effect of recirculation times, is considered in the three different arrangements of maternal and fetal placental vessels.

Light microscopic, electron microscopic and histochemical studies were carried out on the segmental mesometrial arteries of non-pregnant guinea pigs and on pregnant ones at each of the nine weeks of gestation. Pregnant animals show drastic changes in arterial structure and dimensions. Hypertrophy and structural dilatation of the arterial wall are obvious. In midpregnancy, the elastic membranes begin to disappear; only small fragments remain. From the fifth week on, mononuclear cells appear in the media; they form aggregates and occasionally giant cells with signs of phagocytosis in the seventh week of gestation. In the eighth week further degenerative changes can be observed, resulting in widespread destruction of the arterial wall. Deposition of necrotic cell debris is obvious in the ninth week. By this time there appear in the endothelial layer conspicuous single cells, cell aggregates and giant cells with heavily folded nuclei, prominent nucleoli, abundant vesicles, free ribosomes, intracellular lacunae and the histochemical properties of placental trophoblast. These cells in the endothelium are distinctly different from the medial giant cells of mononuclear origin. According to these observations, the segmental mesometrial arteries of pregnant guinea pigs show cytological and structural changes similar to those described for the mesometrial arteries in the hamster and the spiral arteries in man. The results show that, beside structural dilatation, degenerative changes and apparent trophoblastic giant cell invasion occur in the arteries studied. Trophoblastic invasion occurs later than structural dilatation and obviously does not trigger or control the structural dilatation of the segmental mesometrial arteries.

Terminal portions of mesometrial arteries which supply the myometrium and the placenta, respectively, were excised at various stages of the ovarian cycle and pregnancy, as well as after oestrogen treatment, and incubated in solutions containing [3H]thymidine. The incorporation of radioactivity into the acid-insoluble material was measured in order to evaluate the actual rate of DNA synthesis before and during pregnancy and after oestrogen administration. We found that the rate of incorporation rises 30-fold before oestrus and 40-fold in the beginning of pregnancy. A 70-fold rise in incorporation was initiated by 10 micrograms oestradiol benzoate (administered subcutaneously) in dioestrous and ovariectomized animals. We conclude that similar peaks of DNA synthesis in mesometrial arteries occur during oestrus and at the beginning of pregnancy. Oestradiol is capable of inducing the observed surge of DNA synthesis. The results are in agreement with the concept that oestradiol is a chemical regulator of arterial growth during pregnancy.